Distribution of brain-derived neurotrophic factor in cranial and spinal ganglia.
In a previous study we have shown that a subpopulation of primary sensory neurons contain brain-derived neurotrophic factor immunoreactivity. In the present study we investigated the distribution of brain-derived neurotrophic factor and its mRNA in cranial and spinal ganglia at different segmental levels, using immunohistochemical and quantitative reverse transcriptase-polymerase chain reaction techniques. Our results show that there is no significant difference in the percentage of brain-derived neurotrophic factor-immunoreactive neurons in spinal ganglia of different segmental levels. In contrast, more brain-derived neurotrophic factor-immunoreactive neurons were found in placode-derived than neural crest-derived ganglia. The percentage of brain-derived neurotrophic factor-immunoreactive neurons is consistent with the percentage of neurons lost after deletion of brain-derived neurotrophic factor or trkB genes. However, there is no correlation between brain-derived neurotrophic factor mRNA levels and the number of brain-derived neurotrophic factor immunoreactive neurons in these ganglia, suggesting that some neurons synthesize brain-derived neurotrophic factor while others accumulate the factor following its retrograde transport within nerve fibers. In particular, the proportion of brain-derived neurotrophic factor that is derived from extraganglionic sources in the placode-derived ganglia appears greater than that in the neural crest-derived ganglia.
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Department of Human Physiology, Flinders University of South Australia, Adelaide, Australia. pzxfz@cc.flinders.edu.au
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D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D003391:Cranial Nerves / Q000378:metabolism*; D005260:Female; D005724:Ganglia / Q000166:cytology / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009475:Neurons, Afferent / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger